Improvement in keys for electric telegraphs



A.V BAIN. Telegraphc Key- Patented May 12, 1863.

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UNITED STATES PATENT OFFICE.

ALEXANDER BAIN, OF NEW YORK, N. Y., ASSIGNOR TO WILLIAM H. ALLEN, OF SAME PLACE.

MPROVEMENT IN KEYS'FOR ELECTRIC TELEGRAPHS.

Specification forming part of Letters Patent No. 38,530, dated May 12, 1863; antedated December 11, 1862.

To all whom it may concern Y Be it known that I, ALEXANDER BAIN, of the city, county and State of New York, have invented a new and useful Improvement in Electric Telegraph-Keys; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a side view, partly in section, of a key constructed according to my invention, which I call the silent key.7 Fig.2 is a top view of the same. Fig. 3 is a transverse vcrtical section of the same.

Similar letters of reference indicate corresponding parts in the several gures.

It has become-a general custom in this country to read the intelligence transmitted by the electric telegraph, from the sound of the instruments employed, and the consequence is that most persons practically familiar with the operation of the instruments can do this, even at some distance, not only from those instruments used for receiving the intelligence but from the key commonly used for its transmission, and hence it has been very diflicult to preserve secrecy, not only at the oflces or stations where the intelligence has been intended to be received and through which it has passed, but at that from which it has been sent.

The object oi' this invention is to render the operation of the key inaudible, or so nearly so as not to be heardby anyone not in very close proximity to it 5 and to this end itconsists in a certain construction of the key whereby the surfaces of contact by which the circuit is opened and closed are caused to come together with a slidinginstead of with a percussiveaction.

To enable others skilled in the art to make and apply my invention, I will proceed to describe its construction and operation.

A is a Wooden stand.

B is a brass support secured to the stand and receiving the two centerscrews, a a, which constitute the bearin gs for the horizontal rockshaft b, which carries the brass key-lever c. This lever is of the form as that of the key in common use having a downward projection, c, like what is called the hammer,77 fitted with a regulating-screw, d, and having applied it to a spring, e, which keeps the front end of the key raised'when not subject to the pressure of Athe anvil a similar cushion, g. These cushions prevent entirely, or nearly so, any sound being produced by the vibration of the key produced by the alternate downward pressure of the n ger on the ivory knob h at the front end of the key, and ofthe spring e on the rear end thereof.

D is a brass support secured to the wooden stand A on one side of the front end of the supportB, fitted with center screws, j j, to form the bearings of a horizontal rock-shaft, 7c, to which is rmly secured an arm, l, which is kept pressed gently against the side of the lever G by means of a spiral spring, m, which is coiled around the rock-shaft lc, and which has one end secured to the arm l, and the other to the support D.

In one side of the lever C there is inserteda plug, p, of ivory or other non-conducting substance, so arranged with its outer face ush with the side of the lever that when there is no pressure upon the ivory knob on the front end of the lever C, the point of the arm Z bears against the said plug; and above this plug of ivory there is inserted in the lever a plug, a,

of platinum, whose outer face is also iiush with the side ofthe lever C. This latter plug might, however, be dispensed with'.

E and F are the binding-screws by which the ends of the line-conductor are attached, one connected vwith the brass support B, and the other with the brass support D.

W'hile the lever C remains under the uncontrolled influence of the spring e, and the ivory plug is in contact with the point of the arm l, the circuit remains open; but by the operator pressing down on the knob h with his finger, the platinum plug 'n or metallic surface of the lever is brought into contact with the arm Z, and the circuit is closed.

The Inovementof the lever to open and close the circuit is eected noiselessly or so nearly so as not to be heard by any one but the operator, the sliding-movement of the lever in contact with the arm Zbein g inaudible, and the striking of the screw d and hammer l upon their respective cushions being nearly so.

The arm l may be arranged to Work in contact with any other suitable portion of the lever C, and in place of the said arm attached to a rock-shaft a metallic spring attached directly to the brass support Dmay be arranged to operate in a similar manner.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. Providing the lever of a telegraph-key with a plug, p, of ivory or other surface of nonconducting material, operating with a slidingmovement, in combination with an elastic arm, Z, or its equivalent, substantially as and for the purpose herein specified.

2. In combination with the surface of insulating material p, provided on the key and the arm l or its equivalent, the cushions of soft material, fg, applied under the regulating screw and hammer or other stops ofthe key, substantially as and for the purpose herein specified.

ALEXANDER BAIN.

Witnesses:

JAMES LAIRD, E. W. HODGSON. 

